The WebReboot Plugin for Nagios is a suite of commands that can be used within Nagios to monitor a server and take corrective action if necessary via the WebReboot line of products. For example, the plugin can be used to alert you if a host is powered down, versus simply not responding to network requests. Likewise, it can be used to reboot a server if a host fails to respond to ping, or to shut down a server when a critical temperature threshold is exceeded. The commands can be mixed-and-matched with all existing Nagios commands, maximizing total network coverage.
Trojan scan is a simple shell script that allows for simple but relatively effective checking for trojans, rootkits and other malware that may be using your server and network for unwanted (and possibly illegal) purposes. It works by listing all processes that use the Internet with the lsof command (using -Pni flags). This list is then transformed into signatures in the form of process_name:port_number:user. These signatures then are matched against the allowed process defined in the configuration. If any signatures of running processes are found that do not match the allowed signatures, an email report is sent including ps, ls, and optional lsof output.
IPv6 CARE, "IPv6 Compliant Automatic Runtime Environment", provides an environment where applications instantly become IPv6-compliant ('patch' mode, see RFC6535). It can also generate a diagnosis about the IPv6 compliance of an application ('check' mode). It uses an LD_PRELOAD-based library injection technique.
Keywatch is a free, OSGi-based monitoring system that provides the adaptability of a modern monitoring system without being complex or hard to configure. It support agents written in any language, and comes pre-packed with a Perl agent and a set of check scripts. Keywatch also supports Nagios check scripts.
vzhaipd (scoyo's Virtuozzo/OpenVZ HA IP Daemon) is a set of mount/umount Container scripts for Parallels Virtuozzo or OpenVZ that will make sure a HA IP is always present on one of two or more Containers. You can think of it as the poor man's VRRP for Virtuozzo and OpenVZ Containers. Use it for general service availability, software load-balancer failover, etc.